文档介绍：Chapter 2
ics
ics
ics studies drug disposition (处置) and the way the body affects(影响) the drug with time, . the factors(因素) that determine(决定) its absorption, distribution, metabolism and excretion.
§2 药物的体内过程
一、 absorption(吸收)
(一)吸收途径(routes of absorption)
药物从给药部位进入血液循环的过程。
Absorption is the movement of a drug from its site of administration into the blood stream.
1、消化道吸收
(absorption from digestive tract)
口腔
胃
肠
直肠
血液循环
肝脏
首关消除
舌下含化、口服(per os, po)、直肠给药
消化道
首关消除(first pass elimination):
Orally administered (口服) drugs reach the liver via (经过) the portal vein (门静脉). At this stage, or within the small intestine (小肠), the drugs may be extensively metabolized (代谢) and less drugs reach the systemic circulation (体循环); this is known as first-pass elimination or first-pass metabolism.
药物口服后经胃肠粘膜及肝脏的代谢作用,使进入循环的药量减少。
2、消化道外吸收
注射给药(injection)
iv 无吸收过程
吸入给药(inhalation)
局部给药(topical application)
(absorption from parenteral routes)
Intramuscular(肌肉) injection,
Subcutaneous(皮下) injection,
Intravenous(静脉) injection,
(二)影响药物吸收的因素
(factors affecting drug absorption)
1、药物的理化性质和制剂特点
physicochemical properties &preparations
2、给药途径和吸收环境
administration routes &
absorption environment
3、环境pH : pH of the environment (环境)
酸酸碱碱促吸收,酸碱碱酸促排泄
二分布(distribution)
药物吸收后从血液循环到达各组织器官的过程。
Distribution is the process (过程) by which a drug reaches (到达) ans (器官) and tissues (组织) of the body.
影响分布的因素
(一)血浆蛋白结合率
D
+
P
DP
●
暂时贮存形式
●
不易跨膜转运
Factors affecting drug distribution
( binding to plasma protein )
不产生药效
●
D: free drug
DP: bound drug
1、各药的结合率不同
2、有饱和现象(saturation)和
petitive inhibition)
华法林:抗凝血药结合99% 游离1%
华法林+保泰松结合98% 游离2%
出血